Use of GABA uptake inhibitors as anti-tussive agents

ABSTRACT

PCT No. PCT/US97/08948 Sec. 371 Date Mar. 17, 1999 Sec. 102(e) Date Mar. 17, 1999 PCT Filed May 23, 1997 PCT Pub. No. WO97/43902 PCT Pub. Date Nov. 27, 1997Invention is a method of treating cough in a mammal, including a human, which comprises administering to such mammal an effective amount of an inhibitor of GABA uptake.

This application is a 371 of PCT/US97/08948 filed May 23, 1997, and alsoclaims the benefit of U.S. Provisional application Ser. No. 60/018,258filed May 24, 1996.

This invention relates to a method of treating cough in a mammal,including a human, in need thereof which comprises administering to suchmammal an effective amount of an inhibitor of GABA uptake.

BACKGROUND OF THE INVENTION

Gamma-amino-butyric acid (GABA) is a major inhibitory neurotransmitterof the central and peripheral nervous systems and is released into thesynapse on nerve stimulation where it can modulate the activity of otherneurons. For most neurotransmitters, including GABA, neurotransmissionis terminated by the rapid uptake of neurotransmitter via specific,high-affinity transporters located in the presynaptic terminal and/orsurrounding glial cells. Kanner, B. I., et al., Critical Review ofBiochemistry; CRC press; Boca Raton, Fla., 1987; Vol. 22, pp 1-38.

Compounds which inhibit GABA uptake have been shown to be useful in thetreatment of anxiety, epilepsy, muscular and movement disorders andmental and emotional disorders (in U.S. Pat. No. 4,383,999), as well asdemonstrating potent anticonvulsant effects (Yunger, L. M., et al., J.Pharm. Exp. Ther. 1985, 110, 418-427).

Presently, GABA uptake inhibitors are not known as having utility asanti-tussive agents.

SUMMARY OF THE INVENTION

This present invention resides in the discovery that compounds whichinhibit GABA uptake have a therapeutic effect on treating cough in amammal, including a human.

DETAILED DESCRIPTION OF THE INVENTION

All publications, including but not limited to patents and patentapplications, cited in this specification are herein incorporated byreference as if each individual publication were specifically andindividually indicated to be incorporated by reference herein as thoughfully set forth.

Compounds which inhibit GABA uptake are used in pharmaceuticalcompositions as anti-tussive agents.

Illustrative and preferred among the compounds that have GABA uptakeinhibitory activity are the following.

A) ##STR1## which is(R)-1-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid. Thiscompound is disclosed in U.S. Pat. No. 4,383,999, as having GABA uptakeinhibitory activity.

B) ##STR2## which is(R)-1-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-piperidinecarboxylicacid and which is disclosed in Anderson et al., J. Med. Chem. 36, (1993)1716-1725 as having GABA uptake inhibitory activity.

C) ##STR3## which is known as guvacine and which is disclosed inKrogsgaard-Larsen, Molecular & Cellular Biochemistry 31, 105-121 (1980)as having GABA uptake inhibitory activity.

Persons skilled in the art can readily determine if a compound is aninhibitor of GABA uptake by known methods such as those described inU.S. Pat. No. 4,383,999 and Ali, F. E., et al. J. Med. Chem. 1985, 28,653-660. All such compounds are included within the scope of thisinvention.

By the term "treating" as used herein is meant prophylactic ortherapeutic therapy.

By the term "inhibit GABA uptake" as used herein includes the uptake ofGABA by the GABA nerve terminal, glial cells and any GABA cell surfacetransporter.

Compounds of the invention that inhibit GABA uptake were tested fortheir ability to inhibit cough in the general assay described inForsberg, et al., Respiration 59: 72-76 (1992), with the followingexceptions. Citric acid was nebulized for only one minute to theanimals. Coughs were determined by examination of the flow signal andobservation of the test animals.

The following compounds, described in Ali, F. E., et al. J. Med. Chem.1985, 28, 653-660 as potent inhibitors of GABA uptake, were tested forin vivo potency as anti-tussive agents.

Compound 1--N-(4,4-diphenyl-3-butenyl)-3-pyrrolidineacetic acid[compound (1b) in Ali, F. E., et al. J. Med. Chem. 1985, 28, 653-660].

Compound 2--3-piperidinecarboxylic acid [compound (2a) in Ali, F. E. etal. J. Med. Chem. 1985, 28, 653-660].

Compound 3--(R)-N-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid[compound (R)-(2b) in Ali, F. E., et al. J. Med. Chem. 1985, 28,653-660].

Compound 4--1,2,5,6-tetrahydro-3-pyridinecarboxylic acid [compound (3a)in Ali, F. E., et al. J. Med. Chem. 1985, 28, 653-660].

Compound5--N-(4,4-diphenyl-3-butenyl)-1,2,5,6-tetrahydro-3-pyridinecarboxylicacid [compound (3b) in Ali, F. E., et al. J. Med. Chem. 1985, 28,653-660].

Compound 6--cis4-hydroxy-3-piperidinecarboxylic acid [compound (4a) inAli, F. E., et al. J. Med. Chem. 1985, 28, 653-660].

To perform the experiments Male Hartley Guinea pigs weighing between550, and 750 g were placed into a clear plastic exposure chamber with aninternal volume of 6 l. A bias air flow was applied to the chamber at aflow rate of 2 l/min for the duration of the experiment. The changes inairflow inside the box were measured by use of pressure transducer MP45-14 (Validyne Engineering Corp. Northridge, Calif.) that had a rangeof ±2 cm H20 and a pneumotach (consisting of nine 325-mesh screens)mounted on the top of the exposure chamber. Flow signals were output toa preamplifier bank (Buxco Electronics Inc. Sharon Conn.), and routed toa chart recorder (Linearcorder WR 3320 Western Graphtech, Irvine Calif.)for analyses.

An incidence of cough was denoted by a larger than normal inspiration(at least twice normal tidal deflection) followed immediately by arapid, forceful expiration (more than three times the normal excursionfrom baseline). A cough was easily distinguished from animal movement,augmented breaths and gasps by close inspection of the data. Because asneeze and cough have similar flow patterns, they were differentiated byvisual observation of the animals.

Test compounds were administered via the IP route, and the pre-treatmenttime was 30 min. The aerosol was administered to the animals byconnecting a small volume ultrasonic nebulizer (AeroSonic model 5000DDevilbis Sumerset, Pa.) to the bias-flow immediately before the exposurechamber inlet. The animals were challenged with 0.4M citric acid aerosolsolution. A volume of 2 ml of citric acid solution was placed in theultrasonic nebulizer. In one minute approximately 0.5 ml of the solutionwas nebulized to each animal. This has been previously shown to inducethe cough reflex. The incidences of cough in 13 minutes (aerosolizationtime+observation time,) as well as time to onset of the first cough wererecorded.

The guinea pigs treated with a GABA uptake inhibiting compound realizeda significant decrease in the occurrence of cough. Thus, theadministration of a GABA uptake inhibiting compound results in atherapeutic effect as an anti-tussive agent.

This invention discloses inhibitors of GABA uptake and pharmaceuticallyacceptable salts or hydrates or solvates thereof as being useful fortreating cough in mammals, including humans.

An inhibitor of GABA uptake or a pharmaceutically acceptable salt orhydrate or solvate thereof can be administered to a subject in aconventional dosage form prepared by combining an inhibitor of GABAuptake or a pharmaceutically acceptable salt or hydrate or solvatethereof, with a conventional pharmaceutically acceptable carrier ordiluent according to known techniques.

It will be recognized by one of skill in the art that the form andcharacter of the pharmaceutically acceptable carrier or diluent isdictated by the amount of active ingredient with which it is to becombined, the route of administration and other well-known variables. Aninhibitor of GABA uptake or a pharmaceutically acceptable salt orhydrate or solvate thereof is administered to a mammal, including ahuman, in an amount sufficient to prevent or alleviate cough.

The route of administration of the GABA uptake inhibitor is not criticalbut is usually oral or parenteral, preferably oral. Forms of parenteraladministration include; intrarectal, transdermal, intravaginal orintraperitoneal administration. The subcutaneous and intramuscular formsof parenteral administration are generally preferred. The dailyparenteral dosage regimen will be an efficacious, nontoxic quantitypreferably selected from the range of about 0.001 mg/kg to about 20mg/kg of total body weight, most preferably, from about 0.01 mg/kg toabout 5 mg/kg. Preferably, each parenteral dosage unit will contain theactive ingredient in an amount of from about 2 mg to about 150 mg.

The GABA uptake inhibitors which are active when given orally can beformulated as liquids, for example, syrups, suspensions or emulsions,tablets, capsules and lozenges.

A liquid formulation will generally consist of a suspension or solutionof the compound or pharmaceutically acceptable salt in a suitable liquidcarrier(s) for example, ethanol, glycerine, non-aqueous solvent, forexample polyethylene glycol, oils, or water with a suspending agent,preservative, flavoring of coloring agent.

A composition in the form of a tablet can be prepared using any suitablepharmaceutical carrier(s) routinely used for preparing solidformulations. Examples of such carriers include magnesium stearate,starch, lactose, sucrose and cellulose.

A composition in the form of a capsule can be prepared using routineencapsulation procedures. For example, pellets containing the activeingredient can be prepared using standard carriers and then filled intoa hard gelatin capsule; alternatively, a dispersion or suspension can beprepared using any suitable pharmaceutical carrier(s), for exampleaqueous gums, celluloses, silicates or oils and the dispersion orsuspension then filled into a soft gelatin capsule.

The daily oral dosage regimen will be an efficacious, nontoxic quantitypreferably selected from the range of about 0.001 mg/kg to about 20mg/kg of total body weight. Preferably each oral dosage unit willcontain the active ingredient in an amount of from about 2 mg to about150 mg.

While it is possible for an active ingredient to be administered alone,it is preferable to present it as a pharmaceutical formulation.

It will be recognized by one of skill in the art that the optimalquantity and spacing of individual dosages of an inhibitor of GABAuptake or a pharmaceutically acceptable salt or hydrate or solvatethereof will be determined by the nature and extent of the exactcondition being treated, the form, route and site of administration, andthe particular patient being treated, and that such optimums can bedetermined by conventional techniques. It will also be appreciated byone of skill in the art that the optimal course of treatment, i.e., thenumber of doses of a GABA uptake inhibitor or a pharmaceuticallyacceptable salt or hydrate or solvate thereof given per day and durationof therapy, can be ascertained by those skilled in the art of usingconventional course of treatment determination tests.

The method of this invention of treating cough comprises administeringto a subject in need thereof an effective amount of a GABA uptakeinhibiting compound.

The invention also provides for the use of a GABA uptake inhibitingcompound in the manufacture of a medicament for use as an anti-tussiveagent.

The invention also provides for a pharmaceutical composition for use asan anti-tussive agent which comprises a GABA uptake inhibiting compoundand a pharmaceutically acceptable carrier.

No unacceptable toxicological effects are expected when compounds of theinvention are administered in accordance with the present invention.

Following are the results of testing the compounds of this invention.

                  TABLE I                                                         ______________________________________                                        Cmpd #  Dose (mg)                                                                              Route  Control                                                                             Treated                                                                             % Inhibition                                                                          STE                               ______________________________________                                        Compound 1                                                                            20       ip     13.4  7.2   53.13   17.05                               Compound 2 20 ip 13.4 9.75 28.36 21.53                                        Compound 3 1 ip 12.3 6.6 49.23 11.04                                          " 10 ip 13 2.8 78.46 5.65                                                     " 10 po 14.2 8.2 42.25 10.06                                                  " 30 po 14.2 8 43.66 11.78                                                    Compound 4 6 ip 14.7 7.6 48.30 10.67                                          " 20 ip 14.7 4.75 67.69 11.90                                                 Compound 5 1 ip 15.2 15.4 5.79 5.47                                           " 3 ip 15.2 12.4 20.53 9.12                                                   " 30 ip 13.3 1 92.48 4.34                                                     Compound 6 10 ip 13.4 16.3 8.21 8.21                                          " 20 ip 13.4 8.6 35.82 5.58                                                 ______________________________________                                    

The data in the above Table I demonstrates the therapeutic effect ofGABA uptake inhibiting compounds as anti-tussive agents.

All of the compounds that are specifically disclosed herein are knownand can be readily prepared by those of skill in the art.Notwithstanding, this invention relates to all GABA uptake inhibitingcompounds.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following examples are, therefore, to beconstrued as merely illustrative and not a limitation of the scope ofthe present invention in any way.

EXAMPLE 1 Capsule Composition

An oral dosage form for administering a GABA uptake inhibitor isproduced by filing a standard two piece hard gelatin capsule with theingredients in the proportions shown in Table I, below.

                  TABLE II                                                        ______________________________________                                        INGREDIENTS                AMOUNTS                                            ______________________________________                                        (R)-1-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid                                               25 mg                                                Lactose 55 mg                                                                 Talc 16 mg                                                                    Magnesium Stearate  4 mg                                                    ______________________________________                                    

EXAMPLE 2 Injectable Parenteral Composition

An injectable form for administering a GABA uptake inhibitor is producedby stirring 1.5% by weight of(R)-1-[4,4-bis(3-methyl-2-thienyl)-e-butenyl]-3-piperidinecarboxylicacid in 10% by volume propylene glycol in water.

EXAMPLE 3 Tablet Composition

The sucrose, calcium sulfate dihydrate and a GABA uptake inhibitor shownin Table II below, are mixed and granulated in the proportions shownwith a 10% gelatin solution. The wet granules are screened, dried, mixedwith the starch, talc and stearic acid, screened and compressed into atablet.

                  TABLE III                                                       ______________________________________                                        INGREDIENTS            AMOUNTS                                                ______________________________________                                        1,2,5,6-tetrahydro-3-pyridinecarboxylic acid                                                         20 mg                                                    Calcium sulfate dihydrate 30 mg                                               Sucrose 4 mg                                                                  Starch 2 mg                                                                   Talc 1 mg                                                                     Stearate acid 0.5 mg                                                        ______________________________________                                    

While the above descriptions and examples fully describe the inventionand the preferred embodiment thereof, it is understood that theinvention is not limited to the particular disclosed embodiments comingwithin the scope of the following.

What is claimed is:
 1. A method for treating cough in a mammalcomprising administering to said mammal an anti-tussive effective amountof a compound that inhibits GABA uptake.
 2. A method according to claim1, wherein the GABA uptake inhibiting compound is administered at a doseof from about 0.01 mg/kg to about 20 mg/kg.
 3. A method according toclaim 1, wherein the GABA uptake inhibiting compound is administered ata dose of from about 0.1 mg/kg to about 5 mg/kg.
 4. The method accordingto claim 2 wherein the GABA uptake inhibiting compound is(R)-1-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid.
 5. Themethod of claim 2 wherein the GABA uptake inhibiting compound is(R)-1-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-piperidinecarboxylicacid.
 6. The method of claim 2 wherein the GABA uptake inhibitingcompound is guvacine.